Stem and AEPCO Deploy Storage and Solar Project for Arizona Member Co-Op


Project strengthens Stem’s growing foothold in the public power sector; helps Sulphur Springs Valley Electric Co-op deliver reliable clean power to its members

Stem (NYSE: STEM), a global leader in AI-driven clean energy solutions and services, and Arizona Electric Power Cooperative (AEPCO), a not-for-profit, member-owned electric generation and transmission (G&T) cooperative, in partnership with Prometheus Power (Prometheus), a national renewable energy developer, today announced the successful deployment of a co-located storage and solar project to help deliver clean, reliable power to its distribution co-ops and public power members.

Photo Credit: Arizona G&T Cooperatives (AzGT)

Photo Credit: Arizona G&T Cooperatives (AzGT)

The project for Sulphur Springs Valley Electric Co-op (SSVEC), an AEPCO member co-op, includes a 40-megawatt hour (MWh) energy storage system and an existing 20-megawatt (MW) photovoltaic (PV) system that will integrate Athena®, Stem’s award-winning AI-driven clean energy software, to continuously operate and monitor the storage system for maximized performance on a single, unified platform. The SSVEC project is the first of three similarly sized deployments that Stem will collaborate on with Prometheus to provide Stem’s services for AEPCO’s other managing co-ops. All three projects are expected to come online by the end of the year.

“More than 900 electric co-ops across 48 states make up the largest electric utility network in the U.S. The segment is forecasted to be one of the fastest growing segments of the front-of-the-meter (FTM) market through the end of this decade and is projected to represent over 20% of all future storage deployments,” said John Carrington, Chief Executive Officer of Stem. “Stem’s unique combination of AI-driven software, hardware, and services is enabling enhanced value and project returns at scale for co-ops and their members. We are excited to bring our proven capabilities and market experience to AEPCO and their members.”

“As part of our Reliable Energy Plan, AEPCO is focused on strategic investments in renewable energy assets and battery energy storage systems (BESS) to help fundamentally improve, diversify, and strengthen the AEPCO portfolio,” said Patrick Ledger, AEPCO executive vice president and CEO. “With Stem’s proven solar and storage solutions and expertise, we can ensure economies of scale on larger projects so our member co-ops can benefit from the flexibility and reliability of new clean energy resources that will substantially reduce costs and provide more reliable clean energy for the communities we serve.”

“As the largest co-op in Arizona, SSVEC has worked diligently to diversify our energy portfolio from having over 80% coal-generated energy in 2016 to just 25% in 2023 with an estimated 18% generated from renewable sources. These efforts help ensure greater energy independence, reliability, and price stability for SSVEC members, with an overriding benefit of a cleaner environment,” said Jason Bowling, Chief Executive Officer of SSVEC. “Working with AEPCO and Stem to ensure the successful deployment and optimization of our renewable energy assets will help SSVEC continue to honor our commitments of delivering affordable, reliable energy to our 53,000 members.”

“We are honored to have played a pivotal role in the construction of this monumental facility for SSVEC,” said Rohit Garg, Prometheus Manager. “With our developer expertise, we are confident that this project will set a new standard for co-ops implementing utility-scale renewable energy assets, driving forward the adoption of sustainable practices in the energy sector. We are looking forward to working with Stem on deploying future projects for AEPCO."

These follow Stem’s recent co-op project wins, including a 23 MW solar plus 60 MWh storage project for Mohave Electric Cooperative (MEC), an AEPCO distribution co-op, and a 313 MWh standalone energy storage project with Ameresco for a major co-op customer. Stem has booked more than $1 billion of contracts associated with the growing municipal and co-op utility market segment. Most immediately, AEPCO will be hosting a ribbon cutting ceremony in Sahuarita, Arizona on June 13, 2024.

Learn more about AEPCO’s clean energy strategies in the upcoming Stem webinar “AEPCO Leading the Way to Reduce Costs and Improve Reliability for Members,” register at

About Stem

Stem (NYSE: STEM) provides clean energy solutions and services that maximize the economic, environmental, and resiliency value of energy assets and portfolios. Stem’s leading AI-driven enterprise software platform, Athena® enables organizations to deploy and unlock value from clean energy assets at scale. Powerful applications, including AlsoEnergy’s PowerTrack, simplify and optimize asset management and connect an ecosystem of owners, developers, assets, and markets. Stem also offers integrated partner solutions that can improve returns across energy projects, including storage, solar, and EV fleet charging. For more information, visit


AEPCO is the generation, transmission, and energy services provider for electric distribution cooperatives and public utilities in Arizona, California, and Nevada. Headquartered in Benson, Arizona, AEPCO operates with its sister organization, Sierra Southwest Cooperative Services, Inc. (Sierra) under the umbrella of Arizona G&T Cooperatives. AEPCO owns and operates Apache Generating Station, situated in Cochise County, which has been under AEPCO's operation since 1961 and is equipped with existing natural gas and electric transmission infrastructure. For more information about AEPCO and its future projects, please visit

Source: Stem, Inc.

Stem Investor Contacts

Ted Durbin, Stem

Marc Silverberg, ICR

Stem Media Contact

Suraya Akbarzad, Stem

AEPCO Media Contact

Mandi Greenmyer

Sulphur Springs Valley Electric Co-op Media Contact

Marcus Harston

Prometheus Media Contact

Rohit Garg

Source: Stem, Inc.